[Hoppy]

Would it be cheaper to run this with acetic acid (vinegar)? Or, what about swimming pool hydrochloric acid? (Except that hydrochloric acid is much more dangerous to handle.)

 

[Hoppy]

One of the biggest problems with DIY CO2 is waiting too long before replenishing the bottle contents. This lets the ppm of CO2 in the tank water drop too low for too long, and that can trigger BBA growth. It takes self discipline to adapt and follow a rigid routine for replenishing the bottles. When I used DIY CO2, I had bad BBA even with low light, because self discipline isn't one of my big attributes. It worked fine until I got bored with the process and waited too long to do my tank duties. When you use pressurized CO2 the tank of CO2 lasts much, much longer and the pressure gauge on the bottle gives you several days warning that you need to refill it, so laziness is much less likely to get you in big BBA trouble. But, if you can discipline yourself well enough, this looks like a very good low cost CO2 option.

 

[Hoppy]

Thank you for taking the time and effort to report on this. I enjoy experimenting with stuff, too, so I may try this on my 65 gallon low light tank. CO2 is very helpful even with low light, but you don't need the high bubble rates that are needed with high light. The only down side, for me, to using this system is the need for weekly maintenance on the CO2 system. I have learned that I tend to be somewhat erratic about that sort of thing. It is fun to start out, and not much of a chore for the first few months, but later it is easy to slack off too much. And, that would invite BBA to start growing. I have had enough BBA to last a lifetime, so that may be all it takes to discourage me from trying this. But, I still think it looks promising and better than a yeast system.

 

[Hoppy]

Can you tell me what the reason for citric acid and baking soda is for? Is it to add CO2 to the tank? Is this set up for plants only not fish? I have a product from a company names Home Grown that is a chlorine eliminator with vitamin C. I just learned about vitamin C that it is good for the aquarium. Thanks

Vitamin C (Ascorbic Acid) is not recommended for an aquarium. It is a necessary addition to human diets, but I haven't seen where it is good for fish to swim around in, and it isn't a plant food either. It is a pretty weak acid, and expensive compared to citric acid, since it is sold as a food product.

 

[Hoppy]

If you put two needle valves in series it becomes very difficult to adjust them so both are dropping the pressure. A slight change in one needle valve will make the other one either do all of the pressure drop or none of it, or very close to that. Remember, the pressure drop across the needle valve depends on the flow through it. So, when you close down the second needle valve to reduce the flow, that reduced flow causes a smaller pressure drop across the first one. You will end up with a much harder adjustment procedure than with one needle valve.

 

[Hoppy]

I soak the brush then whip it up right on the fittings. You want the bubbles sticking to whatever your checking then watch closely.

Wait about 5-10 minutes and look for tiny collections of bubbles. Leaks that are very serious in a CO2 system can be extremely slow leaks, so it takes time to find them.

 

[Hoppy]

Drop checkers only show a change and are of little to no value to determine co2 levels.

What do you base this on? I have played around with drop checkers long enough to know that they are useful for judging how much CO2 you have, but are not accurate enough to nail down the exact amount you have. There is no method that is available at an affordable price that gives real accuracy with CO2.

 

[Hoppy]

No

Because the system automatically shuts off the flow of acid into the baking soda as the CO2 pressure builds up. It is really an ingenious system! If it would work for a month between recharges it would be virtually the perfect system (in my opinion).

 

[Hoppy]

Is this schematic diagram correct? I copied it from an ad, and modified it slightly, adding a check valve and solenoid valve. I'm going to try this when I get all the "stuff".

EDIT: Corrected schematic

 

[Hoppy]

I corrected the schematic. I still find it a bit difficult to get my mind wrapped around this system :|
Now, I think I finally understand the tee fitting inside the soda bottle - it is an anti siphon device, to prevent siphoning back to the acid bottle. But, I don't see any function for the airstone, or whatever it is, on the end of the one tube.

I'm going to try white vinegar first. I can see the advantage of stronger acid if you want a high bubble rate, but I don't want more than about 2 bbs for my low medium light tank. And, I won't use a diffuser that needs pressure to allow flow of CO2. I will use a little internal filter/powerhead to chop up the bubbles, at least to start out.

 

[Hoppy]

I'm also not sure what that pieces is for . At first I thought it was a block but you can blow through it. I'll have to see if it's a one-way valve, that never occurred to me before. The tee in the other bottle is also where the citric acid enters the baking soda bottle .

Sent from my XT1585 using Tapatalk

I just found a more detailed version of that schematic: that little "ball" is a weight to hold the tube down at the bottom. Good idea, so I will figure out an alternative weight.

 

[Hoppy]

I set up my vinegar/baking soda CO2 system today, and have it in the bath tub to see what I might have done wrong. First I found I had reversed two tube connections, so after fixing that I squeezed the vinegar bottle several times with the shut off valve both open and closed. After about an hour the bubbling started in my bubble counter, and continued very steadily. It adjusted to about 2 bbs. When I closed the shut-off valve, solenoid valve, the bubbling stopped immediately, and the pressure didn't build up at all in 30 minutes, so I believe it works fine. Tonight I will install and connect it to my tank.

EDIT: It is now running on the aquarium, at about 1 bubble per second, which makes a big surge in tiny CO2 bubbles every second. So far, no measurable pressure rise in the bottles, with solenoid valve open or closed. I'm sold - this is the DIY system of the 21st century!

 

[Hoppy]

For the second day now the bubbles have not started when the solenoid valve opens. Both times I had to open the needle valve a bit more, squeeze the vinegar bottle several times, and shake up the baking soda solution. Then I got a huge surge of CO2, and had to readjust the needle valve to reduce it. Something is wrong, but I don't have a clue yet what it is???

 

[Hoppy]

I wish I could help, but I have not read good things about trying to use vinegar instead of citric acid.

Sent from my XT1585 using Tapatalk

That could be the problem. When this finishes I may try citric acid to see what the difference is.

 

[Hoppy]

HI, I am worried. I did everything as per instructions and installed it. But the pressure is raising and now it is 3.2 bar in the gauge and the reaction is still going on. Bottle A is still supplying to bottle B drop by drop. what should I do?

Bump: HI, I am worried. I did everything as per instructions and installed it. But the pressure is raising and now it is 3.2 bar in the gauge and the reaction is still going on. Bottle A is still supplying to bottle B drop by drop. what should I do?

Do you have the tee, labeled 5 in the schematic, installed? I think it is supposed to break the siphon so it is the pressure difference that moves the acid, not the siphon.

 

[Hoppy]

I restarted my set-up using citric acid instead of vinegar. No bubbles, until I fixed a kinked hose. Now it is chugging out a bubble per second or more. Tomorrow I will find out if it can restart after the solenoid valve opens again. I used the standard mix - 200 grams of citric acid in 600 ml of water, and 200 grams of bicarbonate of soda in 200 ml of water.

UPDATE: I find I have to monitor and readjust the needle valve every hour or so, or the bubble rate drops to less than half what I had. Also, it doesn't restart well at all. Today I had to move the in-tank "diffuser" before it would start at all. The reason for this isn't clear yet, and is probably not related to the CO2 generator.

UPDATE: The bubbles seem to have stopped now. If I shake up the baking soda bottle I get a small surge, which doesn't last long. So, I suspect I need to change the solutions. If that is the problem it only worked for about 3 days. I will double the amount of each solution when I change them.

UPDATE: Today I installed a new, all metal check valve in the system, replacing my plastic one. I finally figured out that a big part of my problem was the check valve located down next to the solenoid valve, which allows water to fill the tube from the check valve up to the top of the tank. That makes it very hard for CO2 to ever get back up to the tank again. The new check valve is located up at the top of the tank, and the CO2 flow started very quickly when the solenoid opened. The old check valve still works fine, so I wasted the money buying the new one. I also haven't replaced the liquids in the bottles yet, since it still generates some CO2. Tomorrow I will do that.

 

[Hoppy]

The very small amount of CO2 I add to my low medium light tank has caused my crypts to grow much better, not fast, but now they look much healthier than before, and they are growing instead of just surviving. I am completely sold on using low CO2 concentrations for lower light tanks. My 1 dKH drop checker just gets bluish green, and I'm adding about one bbs of CO2 in a 65 gallon tank. (The drop checker is very blue with no CO2).

 

[Hoppy]

I'm using the same source of citric acid as jrill used: http://www.plantedtank.net/forums/2...et/forums/20-diy/815241-trying-out-citric-acid-baking-soda-co2.html#post7404617 I bought only the 2 pound bag because I wasn't sure how well this would work out.

I dose approximately per the EI Method, but modified as described here: http://www.plantedtank.net/forums/1...tilizers-water-parameters/1005594-fertilizing-65-gal-low-medium-light-tank.html

The CO2 diffuser I'm using is described here: http://www.plantedtank.net/forums/20-diy/1071257-simple-co2-diffuser.html I have used this before and was always satisfied with how it works.

 

[Hoppy]

I have to make needle valve adjustments a couple or more times a day. The bubble rate seems to slowly drop during the day. But, since I am also using Metricide, this changing bubble rate hasn't yet caused a major BBA problem. I have some, on dead leaves, but that is all. I just need to get more involved with trimming the dead leaves.

My reason for doing all of my experimenting with DIY CO2 is because my plants were largely just sitting there and not growing, so I wanted to see if adding even a small amount of CO2 would help, and it has done so. All of my plants are doing much better now, making the tank look like I wanted it to. It just isn't fun having a tank of water with stunted plants in it.

I did some more research about low light with low CO2 yesterday: Tom Barr has said several times in the past that lower light tanks will benefit a lot from getting even low levels of CO2. Like all really serious planted tank hobbyists, he tends to use much more light, much more CO2, and try much more demanding plants. So, he doesn't say much about the benefit of low CO2 anymore. And, a few years ago, you could read an article on the Tropica website that showed that adding any amount of CO2 gives better plant growth. That article seems to have disappeared now, probably because there is little money to be made from promoting low CO2 tanks.

 

[Hoppy]

The problem I haven't found a solution to, yet, is that when the system is off for 16 hours, it won't restart when the solenoid valve opens. To get it to start I have to squeeze some acid into the soda bottle, then shake up the soda bottle. That generates a lot of CO2 at once, but then it works the rest of the day. The baking soda in the bottle never has fully dissolved into the water, so there is a layer of it at the bottom of the bottle. Shaking it mixes it up with the water and the CO2 again starts forming.

I started with 200 g of baking soda in 200 ml water, than renewed it with 400 g of soda in 400 ml of water. I suspect I will need to increase the water to about 600 ml, with 400 g of baking soda. That should result in more of the soda dissolving in the water. What other effects it will have I don't know. The citric acid has been 600 ml of water, 200 g of dry acid each time, and neither time did even half of the acid get used up. So, I should be able to use less total acid - either 200 g in 400 ml or 100 g in 200 ml. I will restart the system tomorrow, so I will decide then which way to go. Any suggestions???

My reasoning is that if all of the baking soda dissolves in the water I won't have a stratified "solution", where the liquid is low on baking soda, but the leftover soda isn't accessible to the acid. I'm also wondering about using a second check valve, at the output of the solenoid valve, to cause the shutdown pressure to be about 1 psi, instead of .5 psi. That might help get the CO2 to flow to the tank.